Ostomy appliances of the so-called one-piece and two-piece types are commonly provided with adhesive faceplates for adhesively securing the appliances to the peristomal skin of the wearers, and moisture absorbing skin friendly hydrocolloid containing adhesives have been used as adhesives for these faceplates.
One early type of skin friendly adhesive is disclosed in U.S. Pat. No. 3,339,546 and consists of a blend of water-soluble and water swellable hydrocolloids, such as polyvinyl alcohol, pectin, gelatine and/or carboxymethyl cellulose and a water insoluble elastic binder, such as polyisobutylene. As the hydrocolloids absorb moisture, such a composition swells and begins to loose it integrity. In order to resist dissolution/disintegration, new hydrocolloid adhesive formulations were suggested, which included physically cross-linked elastomers, such as styrene-olefin-styrene block copolymers and tackifier, see U.S. Pat. No. 4,867,748.
U.S. Pat. No. 6,451,883 describes hydrocolloid adhesives comprising a polymer blend consisting of polybutene (in particular polyisobutylene) and a styrene block copolymer (in particular SIS), and a mixture of hydrocolloids, in particular a mixture of gelatine, pectin and carboxymethyl cellulose. According to this patent an adhesive may be prepared, which do not contain any tackifier or oil, by selecting an appropriate blend of polybutenes and styrene block copolymers.
The adhesive construction according to the invention comprises at least two layers of hydrocolloid adhesives, one adhesive layer with hydrocolloids providing a high moisture absorption capacity and fast initial absorption of moisture as the skin contact layer, and a second adhesive layer with hydrocolloids providing better cohesion than the first adhesive layer.
Adhesive constructions comprising layers of hydrocolloid adhesives are well known in the art:
EP 1 527 789 A1 describes a construction comprising a film layer and at least two layers of hydrocolloid adhesives with different composition.
The prime object of the adhesive construction described therein is to provide a multi-layered adhesive medical appliance that has the attributes of a skin friendly wet tack pressure sensitive adhesive for use adjacent the skin, and a flexible, comfortable, moisture tolerant adhesive that resists degradation after sterilization, and is capable of creating a seal around the stoma in a controlled fashion, for use away from the skin.
The adhesive for use adjacent to the skin is described as an adhesive comprising polyisobutylene and water-soluble or water swellable hydrocolloids.
The adhesive for use away from the skin is described as an adhesive comprising polyisobutylenes or blends of one or more polyisobutylenes and butyl rubber, one or more styrene radial or block type copolymers, mineral oil, one or more water soluble hydrocolloid gums and a tackifier.
It is described that a disadvantage of the known skin-friendly adhesives used adjacent to the skin is that they tend to be somewhat rigid when they become too thick. Thus, it is preferred that the adhesive layer adjacent to the skin is thinner than the more flexible, comfortable, moisture tolerant adhesive, which is used away from the skin.
The layered adhesive construction according to the invention differ from the construction described in EP 1 527 789 A1 in that the characteristic of the hydrocolloids are different in the two layers and in that the continuous phase (see below) is identical or essentially identical in the two layers.
EP 686 381 B2 describes similar adhesive constructions with two layers of hydrocolloid adhesives with different composition. According to this patent, the layer of adhesive securing the adhesive construction to the skin is composed of a skin friendly hydrocolloid containing adhesive that has a relatively low resistance to dissolution and/or disintegration when contacted by stomal fluids, whereas the other adhesive layer placed away from the skin is composed of a relatively soft, easy-deformable and extrudable, adhesive sealant material that is more resistant to dissolution or disintegration by stomal fluids than the material of the skin contact adhesive. From the drawings it is clear that the adhesive layer adjacent to the skin is thinner than the adhesive layer placed away from the skin.
Again the layered adhesive construction according to the invention differs from the construction described in EP 686 381 in that the characteristics of the hydrocolloids are different in the two layers and in that the continuous phase is identical or essentially identical in the two layers of adhesive.
EP 413 250 A1 describes an adhesive construction for use e.g. as part of an ostomy device, which comprises a backing layer and two layers of hydrocolloid adhesive. According to this document, both adhesive layers are in contact with the skin, the adhesive layer contacting the skin in the central part of the device being more than twice as thick as the adhesive layer contacting the skin in the peripheral portion of the construction.
It is indicated that the continuous phase of the two adhesive layers may be the same or may be different. Two different compositions, where the polymeric or continuous phase is different and the blend of hydrocolloids is identical, but present in different amounts, are mentioned for the adhesive layers.
U.S. Pat. No. 4,538,603 also describes an adhesive construction comprising two adhesive layers, which are of different composition, and where the adhesive layer intended for skin contact is thicker than the adhesive layer placed away from the skin. The adhesive layer placed away from the skin is relatively thin and bonded to a foam layer carrying a film on the surface facing away from the adhesive layer. The adhesive construction described herein is constructed be useful for covering exudating wounds or ulcers. It is described that the relatively thick skin contact layer, is composed of ingredients permitting the adhesive construction to remain in place on the skin for several days. The water dispersible hydrocolloids, the water swellable cohesive strengthening agents and the hydratable polymers distributed throughout the adhesive layer gradually becomes hydrated over time. Eventually the adhesive layer becomes so hydrated that the construction can be removed without stripping or macerating the skin around the wound site. The relatively thick adhesive layer to be placed on the skin comprises thermoplastic elastomer, such as low molecular weight polyisobutylene, and hydrocolloids, water swellable cohesive strengthening agents and hydratable polymers, whereas the relatively thin adhesive layer placed away from the skin and bonded to the foam layer may also comprise plastizisers and tackifiers.
Again, the two layers of hydrocolloid adhesives have different continuous phase.
WO 94/15562 describes adhesive constructions consisting of two adhesives, where one adhesive constitutes a layer in the form of an island embedded into the other adhesive layer. It is described how the additional material unit which makes up the island may be of a less cohesive material than the adhesive material making up the rest of the construction.
It is also described how the difference in cohesiveness in the two adhesives used is achieved by using a different continuous phases for the two adhesives, while the mixture of hydrocolloids remains the same in the two layers.
The layered adhesive construction according to the invention differ from the known layered adhesive constructions in that the discontinuous phase (or the hydrocolloids) is different in the two layers, in that the continuous phase of the adhesive is identical or essentially identical for the two layers of hydrocolloid adhesive and/or in that the skin contact adhesive layer is thinner than the adhesive layer interposed between the backing layer and the skin contact adhesive layer.
The adhesive construction according to the invention comprises at least two adhesive layers, one first adhesive layer with hydrocolloids providing a high initial moisture absorption capacity and fast absorption of moisture to the adhesive as the skin contact layer, and a second adhesive layer comprising hydrocolloids providing a good moisture absorption capacity and improved cohesion following absorption compared to the first adhesive layer. The second adhesive layer is at least partly placed behind the first adhesive layer and away from the skin, and is preferably thicker than the first adhesive layer. The thicker second layer of adhesive provides together with its absorption capacity, an effective transportation of moisture from the first adhesive layer and into the second adhesive layer, whereby disintegration and formation of pools of disintegrated adhesive between the skin and the first adhesive layer is diminished.
Due to the absorption capacity of the second adhesive layer, it will swell once it begins to absorb moisture from the first adhesive layer or possibly other sources. This is a particular advantage when the adhesive construction of the invention has a hole for receiving a stoma and is used as a faceplate for an ostomy appliance, because the second adhesive layer may swell and act to provide a seal in a situation where the first adhesive layer has become partly disintegrated in an area around the stoma.
By selecting the same continuous phase for the two adhesive layers, the layers become fully compatible with each other and migration of components from one layer into the other is avoided.